What form do the drivers for this card take? If the code calls DLLs you should be able to rework them for V6.1. If they are code interface nodes, you might be hosed.
Another possibility is to check with the vendor and see if they make new up-to-date DLL-based drivers for the card. You might have to buy them, but they should allow you to get things talking.
Finally, ebay is worth a try. A couple weeks ago there was a guy selling a bunch of DAQ stuff and a copy of LV5 was included in the lot.
Mike...